1. Technical Field
The object of this invention is a device, particularly reduced in size, for the elasticizing of an ear-piece for spectacles. The innovation finds particular, if not exclusive, application in the field of spectacles production, including small metal parts and their fittings.
2. Background Art
Many frames for spectacles are known in the prior art. Some of these frames have devices located close to their hinging for allowing the elastic fastening of ear-pieces to a part of the frame which is known as a front face (WO 9629623A (IDEAL srl Montagner Luciano)). Having such a device located on both sides of the spectacles has the advantage of giving a better fit, because if the ear-pieces exert a low pressure on a person's temples, they are easier to endure by most people, and the spectacles are more adaptable to the different anatomical shapes of each subject. Therefore, the firms in this field are constantly attempting to find innovative and improved solutions, both with regard to function and size of the devices, when compared to the preexisting devices.
For example, a traditional elasticized ear-piece, that found wide acceptance among consumers is disclosed in the European patent application n.79400087.7, in which an elastic hinge was described for a spectacles frame. The elastic hinge comprises a box associated sideways to the ear-piece, the box containing a tie-rod coaxial to the box, and in which an end portion of the tie-rod is threaded, on which is screwed a bushing that ensures the positioning of a spring, while the other side of the tie-rod is in abutment on the inside of a seat in the box.
Another system, conceptually based on the solution provided by the previous patent application disclosure, is disclosed in the Italian utility model n.181221, which has an improved hinge for the articulation of a spectacles frame with an elastically openable ear-piece. A squared support is provided in the frame, on which is inserted a support which is also squared that makes up a shoulder for the compression of a spring.
Finally, the Italian Patent n. 1 147 198 discloses an ear-piece with elastic hinging in which an end of the ear-piece has an axially holed small block within which is inserted one end for the connection of the hinge. Continuing with a reduced diameter, it supports a sharp edge that is fixed inside the borehole while on the back of the borehole is a tension helicoidal spring blocked at an end by a threaded locknut. In such a case, it is possible for the elastic opening of the ear-piece to achieve a certain angle by an elastic yielding of the hinge-like connection.
The common drawbacks noticed in the above-mentioned solutions include excessive complexity of the utilized devices and a total oversizing of the device. Furthermore, notwithstanding that the above-mentioned devices may perform their functions perfectly, they have many problems during the execution phase, such as the manufacturing of the many precision components, as well as during their assembly, each considerably influencing the manufacturing time and cost. Therefore, a main purpose of the firms of the field, has been to obtain elasticizing devices for ear-pieces that are smaller in size, offer good functionality while at the same time reducing the number of components, and decrease the assembly time and costs.
In the numerous recent devices on the market that are more or less effective and in line with the above mentioned principles, there is a solution in which the articulation is an ear-piece with a sliding body containing an elasticizing spring. In more detail, the body, has a square cross section, in which some material has been removed longitudinally from one part of the body to another to obtain opposite thin sheets which define a guide seat, and make up containing walls of a spring. On one side, the spring is placed in abutment on the seat, while on the other, the spring is fastened to a tooth which protrudes outward with respect to the profile defined by the sliding body. Also, the device has a half-hull, is opened on one side and is associated with an ear-piece, and on the inside of the half-hull the sliding body including the spring, is inserted. As a result, the tooth on the longitudinal surface acts as a stop reference. In a traction condition, the articulation causes the body to slide on the inside of the half-hull while causing the tooth to constantly grip along the base of the half-hull to compress the spring, and therefore recall elastically the articulation itself.
It is also very common to fasten to the box, preassembled, on the end of the ear-piece, an elastic yielding group consisting of an articulation on which is screwed a tie-rod coaxial to a spring and fastened on the opposite side by a suitable bushing. As a result, it is possible to notice at least two drawbacks, the need for an adequate size, which influences the weight of the structure, aesthetic not excluded, and the use of screws involve considerable assembling time, and therefore considerable costs. For some ear-pieces, this device is considered valuable and the system is still valid, as seen by its wide use, but for the others, directed to a wider public, the device would not be any more convenient, because of the high costs of the frame. Continuous research in the field, in recent years, was therefore directed towards alternative devices, designed for being produced in great quantities and mainly able to obviate the use of the spring passing the box for the fastening of the elastic yielding group.
It is also known that the French Patent n. 2 517 080 describes a hinge for a spectacles frame, in which a metal core is one with the articulation hinged to the front face. The core is placed, passing from one side to the other, coaxial to a box, and near one end of the box, a housing is provided that is able to contain a helicoidal compression spring. One side of the helicoidal compression spring is positioned in abutment to an annular edge obtained through a working internal to the box, and the other side of the helicoidal compression spring is positioned on the end partially inserted inside the box and which covers the end of the core. The effect obtained by opening the era-piece, consists of the coaxial sliding of the end with respect to the box containing the device. The drawbacks of this latter solution include the fact that some complex components are still required, which make manufacturing and assembling particularly difficult, not excluding some manufacturing costs which would considerably affect the finished product.
Also in the prior art are other known improved elastic yielding devices, which are derived more or less from the previously described solutions, and which exhibit some of the problems related to the large size of the articulation. For example, a two spring ear-piece hinging device is disclosed in EP-A-0462936. It has a double tie-rod spring guide, surrounded by respective helical springs.
The fact is that elasticizing devices are particularly bulky, and unpleasant to see because the ear-piece shape limits and conditions the device's application. Another negative aspect commonly noticeable in the above-mentioned solutions, includes the fact that it is not possible to combine the already finished device directly with the ear-piece and instead involve rather long assembling times. Finally, the traditional ear-pieces have a tie-rod which, because of its shape, allows for excessive slack being inclined as a torsion, that is not much liked by the consumer. The purpose of this invention is to obviate the mentioned drawbacks.